The Urinary System and Homeostasis

The Urinary System and Homeostasis The Urinary System and Homeostasis Bởi: OpenStaxCollege All systems of the body are interrelated A change in one system may affect all other systems in the body, with mild to devastating effects A failure of urinary continence can be embarrassing and inconvenient, but is not life threatening The loss of other urinary functions may prove fatal A failure to synthesize vitamin D is one such example Vitamin D Synthesis In order for vitamin D to become active, it must undergo a hydroxylation reaction in the kidney, that is, an –OH group must be added to calcidiol to make calcitriol (1,25-dihydroxycholecalciferol) Activated vitamin D is important for absorption of Ca++ in the digestive tract, its reabsorption in the kidney, and the maintenance of normal serum concentrations of Ca++ and phosphate Calcium is vitally important in bone health, muscle contraction, hormone secretion, and neurotransmitter release Inadequate Ca++ leads to disorders like osteoporosis and osteomalacia in adults and rickets in children Deficits may also result in problems with cell proliferation, neuromuscular function, blood clotting, and the inflammatory response Recent research has confirmed that vitamin D receptors are present in most, if not all, cells of the body, reflecting the systemic importance of vitamin D Many scientists have suggested it be referred to as a hormone rather than a vitamin Erythropoiesis EPO is a 193-amino acid protein that stimulates the formation of red blood cells in the bone marrow The kidney produces 85 percent of circulating EPO; the liver, the remainder If you move to a higher altitude, the partial pressure of oxygen is lower, meaning there is less pressure to push oxygen across the alveolar membrane and into the red blood cell One way the body compensates is to manufacture more red blood cells by increasing EPO production If you start an aerobic exercise program, your tissues will need more oxygen to cope, and the kidney will respond with more EPO If erythrocytes are lost due to severe or prolonged bleeding, or under produced due to disease or severe 1/5 The Urinary System and Homeostasis malnutrition, the kidneys come to the rescue by producing more EPO Renal failure (loss of EPO production) is associated with anemia, which makes it difficult for the body to cope with increased oxygen demands or to supply oxygen adequately even under normal conditions Anemia diminishes performance and can be life threatening Blood Pressure Regulation Due to osmosis, water follows where Na+ leads Much of the water the kidneys recover from the forming urine follows the reabsorption of Na+ ADH stimulation of aquaporin channels allows for regulation of water recovery in the collecting ducts Normally, all of the glucose is recovered, but loss of glucose control (diabetes mellitus) may result in an osmotic dieresis severe enough to produce severe dehydration and death A loss of renal function means a loss of effective vascular volume control, leading to hypotension (low blood pressure) or hypertension (high blood pressure), which can lead to stroke, heart attack, and aneurysm formation The kidneys cooperate with the lungs, liver, and adrenal cortex through the renin–angiotensin–aldosterone system (see [link]) The liver synthesizes and secretes the inactive precursor angiotensinogen When the blood pressure is low, the kidney synthesizes and releases renin Renin converts angiotensinogen into angiotensin I, and ACE produced in the lung converts angiotensin I into biologically active angiotensin II ([link]) The immediate and short-term effect of angiotensin II is to raise blood pressure by causing widespread vasoconstriction angiotensin II also stimulates the adrenal cortex to release the steroid hormone aldosterone, which results in renal reabsorption of Na+ and its associated osmotic recovery of water The reabsorption of Na+ helps to raise and maintain blood pressure over a longer term 2/5 The Urinary System and Homeostasis The Enzyme Renin Converts the Pro-enzyme Angiotensin Regulation of Osmolarity Blood pressure and osmolarity are regulated in a similar fashion Severe hypoosmolarity can cause problems like lysis (rupture) of blood cells or widespread edema, which is due to a solute imbalance Inadequate solute concentration (such as protein) in the plasma results in water moving toward an area of greater solute concentration, in this case, the interstitial space and cell cytoplasm If the kidney glomeruli are damaged by an autoimmune illness, large quantities of protein may be lost in the urine The resultant drop in serum osmolarity leads to widespread edema that, if severe, may lead to damaging or fatal brain swelling Severe hypertonic conditions may arise with severe dehydration from lack of water intake, severe vomiting, or uncontrolled diarrhea When the kidney is unable to recover sufficient water from the forming urine, the consequences may be severe (lethargy, confusion, muscle cramps, ...A new siglec family member, siglec-10, is expressed in cells of the immune system and has signaling properties similar to CD33 Gena Whitney 1 , Shulin Wang 1 , Han Chang 2 , Ke-Yi Cheng 1 , Pin Lu 1 , Xia D. Zhou 1 , Wen-Pin Yang 2 , Murray McKinnon 1 and Malinda Longphre 1 1 Inflammation and Pulmonary Drug Discovery Department, and 2 Applied Genomics Department, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ, USA The siglecs (sialic acid-binding Ig-like lectins) are a distinct subset of the Ig superfamily with adhesion-molecule-like structure. We describe here a novel member of the siglec protein family that shares a similar structure including five Ig-like domains, a transmembrane domain, and a cyto- plasmic tail containing two ITIM-signaling motifs. Siglec- 10 was identified through database mining of an asthmatic eosinophil EST library. Using the Stanford G3 radiation hybrid panel we were able to localize the genomic sequence of siglec-10 within the cluster of genes on chromosome 19q13.3-4 that encode other siglec family members. We have demonstrated that siglec-10 is an immune system- restricted membrane-bound protein that is highly expressed in peripheral blood leukocytes as demonstrated by Northern, RT-PCR and flow cytometry. Binding assays determined that the extracellular domain of siglec-10 was capable of binding to peripheral blood leukocytes. The cytoplasmic tail of siglec-10 contains four tyrosines, two of which are embedded in ITIM-signaling motifs (Y597 and Y667) and are likely involved in intracellular signaling. The ability of tyrosine kinases to phosphorylate the cytoplasmic tyrosines was evaluated by kinase assay using wild-type siglec-10 cytoplasmic domain and Y!F mutants. The majority of the phosphorylation could be attributed to Y597 and Y667. Further experiments with cell extracts suggest that Src homology region 2 domain-containing protein tyrosine phosphatase (SHP)-1 interacts with Y667 and SHP-2 interacts with Y667 in addition to another tyrosine. This is very similar to CD33, which also binds the phosphatases SHP-1 and SHP-2, therefore siglec-10, as CD33, may be characterized as an inhibitory receptor. Keywords: sialoadhesin; CD33; inhibitory receptor; phos- phatase; siglec. A recently defined group of immunoglobulin superfamily proteins expressed on a variety of cell types have been described as having binding properties that may mediate cell adhesion and cell signaling through recognition of sialyated cell surface glycans [1,2]. This protein family was recently termed siglec for sialic acid-binding Ig-like lectins and is comprised of sialoadhesin (siglec-1) [3], CD22 (siglec-2) [4], CD33 (siglec-3) [5], myelin-associated glycoprotein (MAG, siglec-4a) [6], Schwann cell myelin protein (SMP, siglec-4b) [4], OB-BP2 (siglec-5) [7], OB-BP1 (siglec-6) [8], siglec-7 [9], siglec-8 [10], and siglec-9 [11,12]. Although expression of certain siglecs (e.g. CD33) has long been observed and utilized for diagnosis of some malignant disorders [13], the precise biological functions of the siglec protein family are not well understood. However, because of their structure and expression patterns, siglec proteins are hypothesized to be involved in diverse biological processes such as hematopoiesis, neuronal development and immunity [2]. A trait shared by many of EEccoonnoommiiccss,, tthhee EEnntteerrpprriissee SSyysstteemm,, aanndd FFiinnaannccee February 2002 The University of the State of New York • The State Education Department Albany, NY 12234 www.nysed.gov THE UNIVERSITY OF THE STATE OF NEW YORK Regents of The University C ARL T. HAYDEN, Chancellor, A.B., J.D. Elmira A DELAIDE L. SANFORD, Vice Chancellor, B.A., M.A., P.D. Hollis D IANE O’NEILL MCGIVERN, B.S.N., M.A., Ph.D. Staten Island S AUL B. COHEN, B.A., M.A., Ph.D. New Rochelle J AMES C. DAWSON, A.A., B.A., M.S., Ph.D. Peru R OBERT M. BENNETT, B.A., M.S. Tonawanda R OBERT M. JOHNSON, B.S., J.D. Huntington A NTHONY S. BOTTAR, B.A., J.D. North Syracuse M ERRYL H. TISCH, B.A., M.A. New York E NA L. FARLEY, B.A., M.A., Ph.D. Brockport G ERALDINE D. CHAPEY, B.A., M.A., Ed.D Belle Harbor A RNOLD B. GARDNER, B.A., LL.B Buffalo C HARLOTTE K. FRANK, B.B.A., M.S.Ed., Ph.D. New York H ARRY PHILLIPS, 3 rd , B.A., M.S.F.S. Hartsdale J OSEPH E. BOWMAN, JR., B.A., M.L.S., M.A., M.Ed., Ed.D Albany L ORRAINE A. CORTÉ S-VÁZQUEZ, B.A., M.P.A Bronx President of The University and Commissioner of Education R ICHARD P. MILLS Chief Operating Officer RICHARD H. CATE Deputy Commissioner for Elementary, Middle, Secondary, and Continuing Education J AMES A. KADAMUS Assistant Commissioner for Curriculum, Instruction, and Assessment R OSEANNE DEFABIO Assistant Director for Curriculum and Instruction A NNE SCHIANO The State Education Department does not discriminate on the basis of age, color, religion, creed, disabil- ity, marital status, veteran status, national origin, race, gender, genetic predisposition or carrier status, or sexual orientation in its educational programs, services and activities. Portions of this publication can be made available in a variety of formats, including braille, large print or audio tape, upon request. Inquiries concerning this policy of nondiscrimination should be directed to the Department’s Office for Diversity, Ethics, and Access, Room 530, Education Building, Albany, NY 12234. ii FF FF oo oo rr rr ee ee ww ww oo oo rr rr dd dd T his core curriculum for economics, the enterprise system, and finance supports the State Education Department’s efforts to raise standards in social studies by focusing on Standard 4: Economics, in the Learning Standards for Social Studies. This core curriculum reinforces the key ideas and performance indi- cators for this standard and describes what students should know and be able to do in their study of economics and economic decision making. It outlines the content, concepts, and skills that students should understand and apply throughout their lives. Decisions about what information to include reflect the collaborative efforts of leaders in social studies education, business, finance, and economics education. These decisions were based on the need to pro- vide students with the economic knowledge and skills that will enable them to function as informed and economi- cally literate citizens in our democratic society and in the global marketplace. This new core curriculum includes information about business, entrepreneurship, the enterprise system, finance, and personal finance, in addition to economic theory. Economics, the Enterprise System, and Finance is intended to be used to meet the curriculum mandate of the Board of Regents that requires all students to complete a half-unit course of study in economics or its equivalent as part of their four-unit social studies requirement. Equivalent courses in economics must address Social Studies Learning Standard 4: Economics, specifically the key ideas and performance indicators that define this THE URINARY SYSTEM The urinary system consists of the kidneys, ureters, urinary bladder, and urethra. The kidneys filter the blood to remove wastes and produce urine. The ureters, urinary bladder, and urethra together form the urinary tract, which acts as a plumbing system to drain urine from the kidneys, store it, and then release it during urination. Besides filtering and eliminating wastes from the body, the urinary system also maintains the homeostasis of water, ions, pH, blood pressure, calcium Kidneys The kidneys are a pair of bean-shaped organs found along the posterior wall of the abdominal cavity. The left kidney is located slightly higher than the right kidney because the right side of the liver is much larger than the left side. The kidneys, unlike the other organs of the abdominal cavity, are located posterior to the peritoneum and touch the muscles of the back. The kidneys are surrounded by a layer of adipose that holds them in place and protects them from physical damage. The kidneys filter metabolic wastes, excess ions, and chemicals from the blood to form urine. Ureters The ureters are a pair of tubes that carry urine from the kidneys to the urinary bladder. The ureters are about 10 to 12 inches long and run on the left and right sides of the body parallel to the vertebral column. Gravity and peristalsis of smooth muscle tissue in the walls of the ureters move urine toward the urinary bladder. The ends of the ureters extend slightly into the urinary bladder and are sealed at the point of entry to the bladder by the ureterovesical valves. These valves prevent urine from flowing back towards the kidneys. Urinary Bladder The urinary bladder is a sac-like hollow organ used for the storage of urine. The urinary bladder is located along the body’s midline at the inferior end of the pelvis. Urine entering the urinary bladder from the ureters slowly fills the hollow space of the bladder and stretches its elastic walls. The walls of the bladder allow it to stretch to hold anywhere from 600 to 800 milliliters of urine. Urethra The urethra is the tube through which urine passes from the bladder to the exterior of the body. The female urethra is around 2 inches long and ends inferior to the clitorisand superior to the vaginal opening. In males, the urethra is around 8 to 10 inches long and ends at the tip of the penis. The urethra is also an organ of the male reproductive system as it carries sperm out of the body through the penis. The flow of urine through the urethra is controlled by the internal and external urethral sphincter muscles. The internal urethral sphincter is made of smooth muscle and opens involuntarily when the bladder reaches a certain set level of distention. The opening of the internal sphincter results in the sensation of needing to urinate. The external urethral sphincter is made of skeletal muscle and may be opened to allow urine to pass through the urethra or may be held closed to delay urination. Urinary System Physiology Maintenance of Homeostasis The kidneys maintain the homeostasis of CHAPTER 31 The Urinary System 31-2 Learning Outcomes (cont.) 31.1 Describe the structure, location, and functions of the kidney 31.2 Explain how nephrons filter blood and form urine 31-3 Learning Outcomes (cont.) 31.3 Compare the locations, structures, and functions of the ureters, bladder, and urethra 31.4 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the urinary system 31-4 Introduction Kidneys Kidneys Ureters Ureters Bladder Bladder Urethra Urethra • System functions to remove waste products from the blood • Nephrons filter the blood and form the urine 31-5 The Kidneys • Maintain homeostasis – Remove metabolic waste products – Secrete hormones • Erythropoietin • Renin – Retroperitoneal at level of lumbar vertebrae Kidneys 31-7 The Kidneys (cont.) • Renal sinus – Concave depression on the kidney's surface – Hilum • Renal pelvis – Expansion of the ureter – Divides into calyces Kidney 31-8 The Kidneys (cont.) • Renal cortex – outermost layer • Renal medulla – Middle portion – Divides into renal pyramids • Renal column – between pyramids Kidney 31-10 Nephrons • Renal corpuscle – Glomerulus ~ capillaries – Bowman’s capsule Nephron 31-11 Nephrons • Renal tubules – extend from Bowman’s capsule – Proximal convoluted tubule – Loop of Henle – Distal convoluted tubule Nephron 31-12 Nephrons (cont.) Renal artery Renal vein Afferent arterioles Peritubular Capillaries Glomerulus Efferent arterioles Nephron 31-21 Urine Composition • Mostly water • Urea and uric acid • Trace amounts of amino acids and various ions • Secretion of waste products helps to maintain the acid-base balance 31-22 Apply Your Knowledge Match the following: ANSWER: B Second process in urine formation _ C Substances move from blood _ into renal tubules reabsorption A _ Depends on filtration pressure A Glomerular filtration B Tubular Reabsorption C Tubular Secretion C Third process of urine formation _ A _ First process of urine formation B _ Filtrate flows into the proximal convoluted tubule 31-24 Urinary Bladder • Trigone – triangle on internal floor of bladder • Detrusor muscle – smooth muscle of bladder wall • Micturition – Process of urination – Triggered by stretching of the bladder Bladder 31-26 Urinary Bladder (cont.) • Micturition Impulses to contract urethra  inhibit micturition impulse until ready to urinate Brain stem and cerebral cortex Spinal cord Parasympathetic nerves stimulate detrusor muscle Stretch receptors Bladder distends 31-27 Urethra • Moves urine from the bladder to the outside world • Shorter in females – patient education – Urinate when urge occurs – Drink adequate clear fluids – Wipe front to back – Urinate after intercourse Urethra 31-28 Apply Your Knowledge True or False: ANSWER: T Ureters move urine by peristalsis _ F The detrusor is formed by the openings of the ureters _ and urethra trigone T The process of micturition is triggered when the bladder _ contains about 150 ml urine ureters F The urethra move urine from the kidney to the bladder _ F The urethra is longer in females _ males T Contraction of the detrusor muscle pushes urine from _ the bladder 31-29 Diseases and Disorders of the Urinary System Disease/Disorder Description Acute kidney (renal) failure Sudden loss of kidney function; may be reversible with treatment Chronic kidney (renal) failure Kidneys slowly lose ability to function; not reversible Cystitis Urinary bladder infection; more common in females 31-30 ... attack, and aneurysm formation The kidneys cooperate with the lungs, liver, and adrenal cortex through the renin–angiotensin–aldosterone system (see [link]) The liver synthesizes and secretes the. .. reabsorption of Na+ and its associated osmotic recovery of water The reabsorption of Na+ helps to raise and maintain blood pressure over a longer term 2/5 The Urinary System and Homeostasis The Enzyme... transport The kidneys help regulate blood pressure through Na+ and water retention and loss The kidneys work with the adrenal cortex, lungs, and liver in the renin–angiotensin–aldosterone system